Variable Valve Duration Cam Mechanism for Engine Timing
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Solution Overview
Problem
Existing continuous variable valve lift (CVVL) and variable valve timing (CVVT) systems are complex and costly, making them inefficient for optimizing valve operation based on engine speed.
Innovation Solution
A continuous variable valve duration system with a camshaft, variable phase angle cam portions, and a control mechanism using an eccentric control shaft, worm wheel, and control motor to adjust the relative position of slider housings, allowing for variable valve opening duration without extensive modification to the engine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If general CVVT is used to change valve timing with fixed valve opening duration, then valve timing optimization is achieved, but device complexity increases and manufacturing cost rises
Solution Approach 1:
The valve train is divided into independent adjustable modules: cam portions that can rotate relative to the camshaft, slider housings that position these cam portions, and individual control motors for each cylinder bank. This segmentation allows independent optimization of valve timing and duration for each bank without requiring complex integrated systems.
Solution Approach 2:
The system employs dynamic adjustment mechanisms where cam portions can rotate to different angular positions relative to the camshaft, and slider housings can move to change the effective cam profile. This dynamic capability enables continuous variation of both valve timing and duration, replacing fixed-duration systems with adaptable ones.
2Adaptability or versatility
If continuous variable valve lift (CVVL) is implemented to change valve lift according to engine speed, then valve operation optimization is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The slider housing mechanism serves multiple functions: it positions the cam portions to adjust valve timing, controls the effective cam profile to vary valve duration, and can accommodate different cam configurations for various engine operating conditions. This multi-functionality reduces the need for separate mechanisms for each adjustment type.
Solution Approach 2:
The system uses the existing camshaft rotation and valve train mechanics as the basis for adjustment, rather than requiring entirely new actuation systems. The control motors simply rotate cam portions relative to the camshaft, leveraging the natural rotational motion already present in the engine.
3Productivity
If complex valve control systems are used to achieve optimal valve operation, then engine performance is improved, but productivity and production cost are negatively affected
Solution Approach 1:
The system replaces complex mechanical cam timing adjustment mechanisms with electric motor-driven rotation of cam portions. This substitution allows for precise, programmable control of valve timing and duration without requiring complex mechanical linkages, reducing manufacturing complexity while maintaining performance.
Solution Approach 2:
The system achieves performance optimization by changing key parameters: the angular position of cam portions relative to the camshaft, the position of slider housings, and the effective cam profile. These parameter changes allow continuous adjustment of valve timing and duration to match operating conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system simplifies valve train construction, reduces size, enhances productivity, and lowers production costs by allowing valve duration adjustment based on engine operation conditions without altering the engine's fundamental design.
Implementation Method 1
a worm wheel connected to the eccentric control shaft, a worm gear engaged with the worm wheel
Data Source
AI summary
A continuous variable valve duration system may include a camshaft, a cam portion having a cam is formed thereto. The camshaft is inserted to the cam portion such that a relative phase angle with respect to the camshaft is variable. The camp portion has a cam cap engaging portion, and an inner bracket transmits rotation of the camshaft to the cam portion. A slider housing has the inner bracket rotatably inserted thereto, of which relative position with respect to the camshaft is variable, and of which a control slot is formed. Cam caps rotatably mount the cam cap engaging portion to a cylinder head, and a control portion comprising an eccentric control shaft inserted into the control slot. A worm wheel is connected to the eccentric control shaft, and a worm gear engaged with the worm wheel and a control motor selectively rotates the worm gear so as to change relative position of the slider housing with respect to the camshaft and a cylinder head cover of which a motor mounting portion where the control motor is mounted thereto.